Certified joint true copy of birth certificate with remarks/annotation based on the legitimation by subsequent marriage.

Verify the original birth certificate at the Philippine Statistics Authority (PSA). If it yields negative result, secure the birth certificate from C/MCR Office where the child was originally registered (Certified Photocopy).

Verify the marriage contract of parents at PSA. If it yields negative result, secure the marriage contract from C/MCR Office where the marriage was solemnized (Certified True Copy).